They sure do! I just got them and, upon first testing, they were giving me a re-cycle time 1/2 of what the eneloops do. That's as fast as having a battery pack (such as Quantum) connected to the flash! The problem was that when I went to shoot the wedding yesterday, they died in like 10 minutes. I think two of the four batteries may be bad; need to look into that further.

I had them and used them at weddings. Super fast recycle, as fast as with a battery pack. However. You get about 200 pops out of them shooting slowly and I killed a fresh set with under 80 shots shooting fast and when they came out they literally burnt my hand. Chucked them after that...

Mark_L wrote:
Fast recycle but low capacity, nimh is still the best choice

It's the very fast recycle that intrigues me. One of our shooters is having a situation where he's getting a lot of black frames (during the reception introductions) where the flash doesn't go off because it can't recycle fast enough to keep up with the people being introduced in. His flash, 430exII, doesn't take a battery pack. The nickel zinc batteries recycle the 430 as fast as NiMH batteries in a battery pack!

After testing the batteries one-by-one in non-photo devices, I have found that one of the four batteries I received was defective. So this may explain my getting only a limited number of flashes out of the set of batteries.